1. Field of the Invention
The present invention relates to a slide mechanism, and more particular to a slide mechanism of a linear transmission apparatus applied in an electrical chair or an electric hospital bed.
2. Description of Prior Art
In general, an elderly or a handicapped usually does not have sufficient strength to support them to stand up from a seat, but usually needs another person to assist them. If a linear transmission apparatus is applied to the seat to constitute an electrical chair, then the height or angle of elevation can be adjusted to give much more convenience to the elderly and handicapped users. Thus, the subject of a slide mechanism of a linear transmission apparatus requires extensive researches and developments.
In a conventional slide mechanism of a linear transmission apparatus as disclosed in Denmark Pat. Publication No. 200001377, the transmission apparatus includes an actuating mechanism, a guide screw and a slide mechanism. The slide mechanism includes a fixing base, a guide rail and a slide element, wherein the fixing base has a through hole for passing the guide screw, and the horizontally disposed and U-shaped guide rail is covered onto the exterior of the guide screw and connected to the fixing base. The slide element is sheathed onto the exterior of the guide rail, and a nut secured to the guide screw is formed inside the guide rail.
In another conventional slide mechanism of a linear transmission apparatus as disclosed in U.S. Pat. No. 5,927,144, the transmission apparatus includes an actuating mechanism, a guide screw and a slide mechanism. The slide mechanism includes a fixing base, a pair of upper and lower guide rails and a slide element, wherein the fixing base has a through hole for passing the guide screw, and the upper and lower guide rails are covered onto the exterior of the guide screw and connected to the fixing base, and the slide element is sheathed onto the exterior of the upper and lower guide rails, and the guide rail includes a nut disposed therein and secured to the guide screw.
However, the practical applications of the aforementioned conventional slide mechanisms of a linear transmission apparatus still have the following problems. Since the guide rail has a long open slot, not only allowing dusts, moisture or foreign substances to enter into the apparatus, but also reducing the life expectancy greatly. Furthermore, the operation of the apparatus generates annoying noises. The slot of the guide rail is provided for the slide element to slide therein, and thus accidents or injuries including the fingers of a user or a child being clamped accidentally occur very frequently. In an integrally formed guide rail as disclosed in Denmark Pat. Publication No. 200001377, the weight of the guide rail is heavy and the cost is high. A frame of the slide element and the nut are connected by one or two ribs, and the strength of the connection is weak and insufficient to hold the weight or bear a sudden impact of an overweight user. As a result, the ribs between the nut and the frame are cracked or damaged frequently, and the users get hurt very often. The prior arts definitely need improvements.